Water in an aquarium needs to contain dissolved oxygen in order to support fish life. Known systems for oxygenating aquarium water suffer from various disadvantages. For example, air may be bubbled through the water, but control of bubble systems is difficult.
Dissolved oxygen may be provided by controlled decomposition of a solution of hydrogen peroxide, and a system of this type is shown by Sochting, U.S. Pat. No. 4,466,556. The system of the Sochting patent is complex, and has at least two steps (each conducted in a separate container) of catalytic decomposition of hydrogen peroxide. Sochting uses a catalyst of activated charcoal or manganese dioxide bound to a suitable carrier to aid in each stage of the hydrogen peroxide decomposition. The Sochting apparatus employs a pellet of this catalyst inside the container, and the container either stands inside a dish or another container made of a ceramic which has catalyst embedded in it, or has such a catalyst-containing dish mounted on it. The catalyst-containing ceramic decomposes the peroxide into oxygen and water.